title: IL-2 dependence of the promotion of human B cell differentiation by IL-6 (BSF-2).
abstract: The effect of rIL-6 on the growth and differentiation of highly purified human peripheral blood B cells was examined. IL-6 alone induced minimal incorporation of [3H]thymidine by unstimulated or Staphylococcus aureus (SA)-stimulated B cells and did not augment proliferation induced by SA and IL-2. Similarly, IL-6 alone did not support the generation of Ig-secreting cells (ISC) or induce the secretion of Ig by unstimulated or SA-stimulated B cells. However, IL-6 did augment the generation of ISC and the secretion of all isotypes of Ig induced by SA and IL-2. Maximal enhancement of B cell responsiveness by IL-6 required its presence from the initiation of culture. Delaying the addition of IL-6 to B cells stimulated with SA and IL-2 beyond 24 h diminished its effect on ISC generation. However, increased Ig production but not ISC generation was observed when IL-6 was added to B cells that had been preactivated for 48 h with SA and IL-2. This effect was most marked when the activated B cells were also stimulated with IL-2. IL-6 in combination with other cytokines such as IL-1 and IL-4 did not induce the secretion of Ig or generation of ISC in the absence of IL-2. Moreover, antibody to IL-6 did not inhibit the effect of IL-2 on the growth and differentiation of B cells stimulated with SA, but did inhibit the IL-6-induced augmentation of Ig secretion by B cells stimulated with SA and IL-2. IL-6 alone enhanced T cell dependent induction of B cell differentiation stimulated by PWM. Part of this enhancement was related to its capacity to increase the production of IL-2 in these cultures. These results indicate that IL-6 has several direct enhancing effects on the differentiation of B cells, all of which are at least in part dependent on the presence of IL-2. In addition, IL-6 can indirectly increase B cell differentiation by increasing IL-2 production by T cells.
authors.affiliation: Department of Pediatrics, Harold C Simmons Arthritis Research Center, Dallas, Texas.
authors.forename: J B
authors.initials: JB
authors.lastname: Splawski
authors.forename: L M
authors.initials: LM
authors.lastname: McAnally
authors.forename: P E
authors.initials: PE
authors.lastname: Lipsky
mesh_terms: D000917:Antibody Formation / Q000187:drug effects; D001402:B-Lymphocytes / Q000166:cytology*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004357:Drug Synergism; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology*; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects; D011994:Recombinant Proteins; D013211:Staphylococcus aureus / Q000276:immunology
chemical_list: D007375:Interleukin-1; D007376:Interleukin-2; D015850:Interleukin-6; D011994:Recombinant Proteins; D015847:Interleukin-4